1. Field of the Invention
The present invention relates to a drive control device mounted to a hybrid electric vehicle having an engine and a motor for a running power source, and the drive control device performs a drive control of the engine and the motor.
2. Description of Related Art
A conventional display device mounted to a hybrid electric vehicle causes a display unit to display an accelerator pedal position that changes with an operation amount of an accelerator pedal, and the display unit also displays a certain accelerator pedal position, at which a running mode is switched between an EV running (or motor running) mode and an HV running (or hybrid running) mode (see, for example, JP-A-2008-74321).
Also, in a conventional drive control device of a hybrid electric vehicle, a running history, such as a vehicle speed, is collected for each of the predetermined sections, and schedule of a target value (target SOC) of a charge amount of the battery for the hybrid electric vehicle is determined for each of the predetermined sections based on the learned running history and a road state in the route to the destination in order to minimize the fuel consumption to the destination. Then, the drive control device performs drive control of the engine and the motor based on the schedule in order to cause the charge amount of the battery of the hybrid electric vehicle for each section to coincide with the target SOC (see, for example, JP-A-2000-333305 corresponding to U.S. Pat. No. 6,314,347).
In the vehicle mounted with the device of JP-A-2008-74321, the driver is capable of looking at the display unit and of often executing accelerator operation that enables an EV running mode, and thereby the driver is capable of improving the fuel efficiency.
However, the device of JP-A-2000-333305, which in advance determines the schedule of the control target value for each section in the route to the destination in order to minimize the fuel consumption, and which executes the drive control of the) engine and the motor based on the schedule, may achieve more enhanced fuel efficiency than the device of JP-A-2008-74321, which merely often executes the accelerator operation that enables the EV mode running. For example, in general, in a stopping frequency section, in which the vehicle often stops, the fuel efficiency is more effectively enhanced when the EV mode running is more often used than the HV mode running. However, if the EV mode running is excessively used in the section upstream of the stopping frequency section, the residual amount of the battery may be reduced to a value lower than a certain threshold value in the stopping frequency section, and thereby the battery may be required to be charged by starting the engine while the vehicle stops in the stopping frequency section. As a result, the fuel efficiency may deteriorate disadvantageously. In the above case, the schedule is made in order to use the HV mode running often in the section upstream of the stopping frequency section, and in order to use the EV mode running in the stopping frequency section. By operating the vehicle based on the schedule, it is possible to improve the total fuel efficiency of the entirety of the sections.
However, the driver is incapable of recognizing the running mode suitable for the enhanced fuel efficient running of the vehicle position in view of the entirety of the sections in the device of JP-A-2000-333305 disadvantageously, and thereby, for example, the driver may not depress the accelerator pedal properly. More specifically, even when the vehicle runs on the section, in which the charge of the battery for the motor executed by deeply depressing the accelerator pedal is suitable for the enhanced fuel efficient running, the driver may slightly depress the accelerator pedal in the intention of more often using the EV mode running. As a result, the fuel efficiency may not be achieved as planned disadvantageously.